1. Technical Field of the Invention
The invention relates to a work carrier changeover device for machine tools, with a work carrier transfer device for moving the work carrier between a machining station and a tooling station, wherein the work carrier transfer device has a coupling element rotatable around a vertical axis and with two opposing coupling points for the coupling of work carriers.
2. Prior Art
In a changeover device of this kind known from EP 0409085 B1, a coupling element for work carriers, capable of rotating through 180°, is located on the machine itself, while a linear work carrier traversing station is also required to bring the work carriers, each provided with workpieces, to the machining station. Besides the poor accessibility to the working area due to the direct mounting of the changeover device on the machine, the traversing station takes up a large amount of space. Subsequent attachment to a standard machine is generally impossible. Attachment to the machine brings about inadequate decoupling between machining station and setting-up station so that there is a danger that, during the setting-up process, i.e. during the loading of the work carrier with new workpieces at the setting-up station, machining at the machining station is adversely affected. A further drawback lies in the fact that, due to the transfer by means of swivel and linear movements, the work carrier changeover takes an unsatisfactory length of time.
Known from DE 19513827 A1 and DE 10020804 A1 are work carrier changeover devices which are fully integrated in the machine and which require no linear movements. In this case, subsequent attachment to a standard machine would mean even greater expense, which would make such attachment virtually impossible. In actual-time parallel tooling, the integration of tooling station and machining station means that vibrations and forces are transmitted to the machining table, which has a negative effect on the accuracy of machining. Automatic loading by means of a handling system is therefore even more problematic. Another drawback is the poor accessibility to the machining station due to the platen shuttle being rigidly attached to the machine.
Finally, EP 1084794 A1 discloses a work carrier changeover device with a handling system in which the work carrier is brought from a pallet shelf unit to the machining station by a loading unit. While this certainly leads to good decoupling of machining station and tooling station, and provides good accessibility to the working area, there is a very high space requirement together with an expensive and cost-intensive design, while the work carrier changeover requires a relatively large amount of time.